تقنية السيارات الحديثة: New Chassis Control is that make the driver more comfortable

What is New Chassis Control?

A car requires suspension, steering and brakes for everyday driving tasks. These systems or components are collectively known as the chassis. The technology that controls the chassis has made major strides since the birth of the car. In particular, computer technology has greatly improved safety and reliability by electronically controlling the chassis, allowing the adoption of features such as Electronic Stability Control.

Nissan wanted to develop chassis control technology one stage further by adding additional chassis controls to help deliver a fun, confident and comfortable driving experience. The technology Nissan created is the New Chassis Control, which consists of the following three technologies.

Active Ride Control

By controlling the engine (drive force) and brakes, this technology can improve driver confidence and comfort when driving over uneven surfaces.

Realizing a more comfortable ride

When driving, a vehicle will encounter large and small bumps on the road. As the vehicle passes over certain bumps, passengers may feel a fore-aft pitching motion. The Active Ride Control moderates this by controlling the engine and brakes, delivering a smoother driving experience.

Technology Functionality

When the driver depresses the accelerator pedal and engine torque is increased, the front half of the vehicle rises up slightly. Conversely, when the foot is taken off the accelerator pedal and engine torque is reduced, the front of the vehicle lowers back down. The raising and lowering of the front of the vehicle results in the vehicle exhibiting pitch behavior.

Active Ride Control takes advantage of this phenomenon to counteract the pitching caused by bumps. The engine torque is varied slightly according to the bumps in the road surface, which decreases the pitching motion of the vehicle and allows the vehicle’s occupants to have a more enjoyable driving or riding experience.

In addition, the vehicle suspension is fitted with shock absorbers which dampen the vertical and pitch motions of the vehicle. When dampening is strong, the motion caused by bumps on the road surface is quickly reduced. Conversely, with weak dampening, the motions caused by bumps can continue for a long time.

Nissan discovered that when the brake is applied, it has the effect of strengthening the dampening of body motion. Active Ride Control includes technology developed to reduce vehicle pitching when passing over a bump by automatically applying a very small amount of braking. The amount of braking is not enough to slow the vehicle down appreciably, but still results in faster dampening of the pitch motion than the vehicle using shock absorbers alone. With Active Ride Control, the pitching that follows when a vehicle passes over a bump is decreased in amount and duration, and the driving experience becomes more comfortable.

Technology Configuration

When a vehicle passes over a bump, the wheels speed fluctuates slightly when compared to the same vehicle driving on a flat surface. Using sensors to detect the change in the speed of the wheels, the system determines when the vehicle is moving up and down.

When the pitching is minor, ride quality can be improved by increasing or decreasing the engine torque. When the pitching is greater, the system applies the brakes and this helps minimize the body motion of the vehicle. The engine torque variations and the brake applications are small and smooth. They calm the vehicle body motion but do not result in appreciable increases or decreases in vehicle speed. This allows drivers and passengers to simply enjoy a more comfortable driving and riding experience.

Active Engine Brake

This technology supports drivers by adding engine braking and reducing the burden on the driver when cornering or braking.

Achieving smooth braking and cornering

When it is necessary to reduce vehicle speed, drivers depress the brake pedal and adjust their brake pedal effort until the vehicle is at the desired speed. If the vehicle speed does not drop to the desired level, drivers must depress the brake pedal again or increase their braking effort.

The Active Engine Brake system assists drivers in reducing the vehicle speed to the desired speed. The system smoothly adds small amounts of engine braking to assist the brakes. The system decreases the frequency and effort required to brake the vehicle, which makes driving easier and more comfortable.

Technology Functionality

When cornering or stopping, it is necessary to reduce speed. Vehicles equipped with the Active Engine Brake system measure the vehicle speed along with steering and braking inputs. Using these measurements, the system then automatically adjusts the level of engine braking, decreasing the time and effort the driver must take to slow the vehicle. As a result, it can reduce the amount of brake applications required by the driver, allowing the driver to have a more stress-free driving experience.

Technology Configuration

When cornering, the system estimates the desired vehicle path based on vehicle speed and the driver’s steering input. A target speed appropriate for the estimated trajectory is determined from these measurements. Engine braking is then smoothly and automatically applied when the actual vehicle speed is higher than the target speed.

The Active Engine Brake system adjusts the amount of engine braking to be applied by varying the CVT (Continuously Variable Transmission) gear ratio. When braking and coming into a stop, the system calculates the appropriate deceleration level by measuring the driver’s brake pedal effort. It then smoothly adjusts the gear ratio to add subtle engine braking in order to aid deceleration.

Active Trace Control

This technology helps the driver feel more confident when cornering by controlling the braking on each of the four wheels in response to the driving circumstances, based on the driver's steering, acceleration and braking on winding roads or when entering or exiting an expressway. This can help provide the driver with a more optimal line through a turn.

Delivers confident cornering

Negotiating a corner along the intended path (trajectory) is a rewarding driving experience. But it can be difficult to maintain that steered path if there are variations in the road/turn, because a driver has to control three things simultaneously: acceleration, braking and steering. To assist drivers, the Active Trace Control system can apply braking automatically to each wheel, helping to keep the vehicle on the cornering line as steered. The system helps drivers smoothly maintain control, so they are able to relax and drive around corners more confidently.*

Technology Functionality

Active Trace Control can engage at any point in the corner (entry, mid-corner or exit) if it determines that the vehicle is departing from steered path. By automatically and smoothly applying small amounts of braking to individual wheels, the system corrects the vehicle trajectory to match the driver’s commands, so the driver can maintain confidence while cornering. For example, if the vehicle enters the corner too quickly, the vehicle may tend to move to the outside of the curve. Active Trace control will gently and smoothly correct the vehicle’s cornering line to help bring it back to the steered path. The system can also engage when exiting the corner. For example, if the driver accelerates out of the curve too quickly and the vehicle tends to move to the outside, Active Trace Control will smoothly brake the inside wheels to help gently bring the vehicle back to the steered path.

Technology Configuration

Active Trace Control is based on Vehicle Dynamics Control (VDC) technology (also known as “Electronic Stability Control,” or ESC). The VDC system constantly monitors the driver’s steering inputs, the speed of the wheels, the vehicle yaw rate and the lateral and longitudinal forces acting on the vehicle to deliver added safety when it is needed. Active Trace Control is a comfort feature that uses the same information and brings the technology into everyday driving situations, using it to deliver a comfortable and confident driving experience. Based on information acquired from the VDC system, Active Trace Control detects when the vehicle is departing from the steered path. The system then applies gentle, smooth braking to individual wheels to help bring the vehicle back into the correct cornering line. The amount of braking is small and does not affect the vehicle speed appreciably, but aids cornering by correcting the speed and/or adding yaw when needed. The system will only activate when it detects that the vehicle has departed from the path the driver desired via his or her steer inputs. In this way, Active Trace Control helps keep the vehicle in line and increases driver confidence and enjoyment.